📖 what
What is a galaxy?
SpaceAstronomyPhysics
Quick Answer
A galaxy is a vast system of stars, gas, dust, and dark matter bound together by gravity. The observable universe holds hundreds of billions of them.
The Full Story
A galaxy is an enormous, gravitationally bound collection of stars along with gas, dust, and unseen dark matter. Our own galaxy, the Milky Way, contains an estimated 100 to 400 billion stars. Galaxies come in shapes including spirals, ellipticals, and irregulars, and most have a supermassive black hole at their centre. They are the basic large-scale building blocks of the cosmos, and the observable universe is thought to contain hundreds of billions — perhaps as many as two trillion — of them.
Key Facts
1.The Milky Way holds an estimated 100 to 400 billion stars
2.Galaxies come in spiral, elliptical, and irregular shapes
3.The observable universe may hold up to two trillion galaxies
YouTube Angle
Suggested video title for this topic:
"What Is a Galaxy — Islands of Stars in the Cosmos"